Optimum Research On Technology Of Peak-to-average Power Radio Reduction In OFDM System

Orthogonal Frequency Division Multiplexing(OFDM) technology is known for its convenience of implementation, as well as other characteristics such as the high speetrum efficiency, the anti-multipath fading capability and its unique effective suppression of the inter-symbol interfrence(ISI) and the inter-carrier interference(ICI), which has been successfully applied in rnany high-speed wireless communication systems and become the next generation mobile communication system standard. Nevertheless, a higher peak-average power ratio(PAPR) of the equipment to the system brought about a heavy burden of OFDM, which greatly limits the widespread application of OFDM technology. Naturally, so how to reduce the high PAPR of OFDM signal is the important issue.The paper started with the basic theory of OFDM technology, Firstly, the most popular three kinds of PAPR reduction techniques had been studied in detail, including amplitude clipping, active constellation, partial transmit sequence, selected mapping, pulse shaping, coding, etc. These techniques achieve PAPR reducion at the expense of transmit signal power increase, bit error rate increase, data rate loss, computational complexity increase, etc. They also had different performance. We made careful analysis and simulations for each technique. Secondly, focused on low complexity partial transmit sequence(PTS) schemes to achieve PAPR reduction and made careful simulations and verifications for some existing improved PTS schemes in the paper. Then a improved PTS scheme based on Tellambura PTS was proposed and simulation results showed that the improved PTS scheme could achieve good PAPR reduction performance at low computational complexity. In addition, based on some problems of out of band emission, in band noise and computational complexity in amplitude clipping, a scheme that combined pulse shaping technology and repeat clipping and filtering technology was proposed to achieve PAPR reduction from the balanced perspective of the system. Simulation results showed that the proposed scheme could effectively inhibit the clipping noise to the system ber performance and improve spectrum. By selecting the system parameters properly, it could achieve a good compromise between complexity of computation and PAPR performance. Besides, the decoding in receiver is simple, so does not cause a large burden of the system. Finally, this paper summarized the work I have done, pointed out the remaining problems and gave some suggestions to the next phase of work.